The present invention relates to condition monitoring, particularly for monitoring temperatures and pressures in environments which are not suitable for electrically operated transducers.
While it is quite common to monitor temperatures and pressures in many types of systems by means of electrically operated transducers, such as thermocouples a piezoelectric devices, there are many types of equipment in which, because the presence of high voltages, transducers of this type cannot be satisfactorily employed.
However, it has proven difficult to monitor such parameters in such environments with purely nonelectrical transducers. Optically coupled temperature transducers which have been previously proposed include: those which are constructed to sense black body emission and which can be employed only to monitor higher temperatures and require the use of expensive fibers; elements which compare the quenching of different fluorescent lines or which measure temperature dependence of decay, which require special light sources and expensive fibers; and elements which measure jacket loss and are of limited accuracy.